Caliber ISP mid power

Ok so I recently bought a LARGE collection from someone and ended up with casings, reloads, kits, extra parts, a launch pad. Nedless to say, quite a lot.
Some of the kits were complete but slight damage, such as the Caliber ISP.
Mostly the damaged parts involve the payload section so here is my question.
How different would flight stability be affected if I built it without that whole section and made the motor mount 29mm instead of 38mm.
Understand I have no intentions of needing a 38mm rocket any time soon and don't really want to replace parts.
Would it be as simple as adding weight to replace what was lost by removing the payload section or maybe not even necessary to add weight?
Any help or ideas appreciated.
Thanks

So long as you have an adapter for the motor and adjust the weight to maintain stability you'll do OK

Making the rocket shorter reduces the stability (CG and CP both move down)
Using a lighter motor increases the stability (CG moves up)

Since you are doing both you need to make sure one balances off the other and you have at least 1 caliper (body diameter) of stability

Also, since you are moving to a smaller motor make sure the motor you use has sufficient thrust to handle the rocket with any added weight. The rule of thumb is 5 to 1

That must be an older Caliber ISP. Mine has a 54mm motor mount even though I have only flown 38mm motors in it. It is a fantastic rocket!! I would suggest leaving the 38mm motor mount and using a reducer for 29mm loads. This at least gives you the option of putting something bigger in down the road should you ever decide to add the e-bay and payload sections.

My Caliber ISP is 23 years old and 54mm, and that's how it's listed on the LOC website.

Ya I think it is 54, not sure why I put 38

Only reason I thought of reducing the length was because I was hoping it might open up more engine possibilities for 29mm. The only engine it recommends at 29mm is G80.

My suggestion is take the easy way out.... Download a copy of Open Rocket ( https://openrocket.sourceforge.net/ ) , get the Rocksim file from the web ( https://www.rocketreviews.com/unknown-caliber-isp.html ) and run your modifications through simulations. You may find that you don't need to dump the payload section at all. You can then use OR to run simulations on the other rockets in the collection and see what you find.

That's actually one of the reasons I was asking. I tried downloading OR and for some reason I cannot get the thing to run on my computer.
Just my luck :-(

The Caliber ISP with a 29mm motor mount and no payload section is a Forte. It'll be a fine performer on F, G, H, and I motors.

But you could also build it without the payload section (for now) and leave the motor mount 54mm, flying 29s with an adapter. Then if you decide you ever want a Caliber ISP, plug one on and off you go 8)

Skytime-is-fine said:

That's actually one of the reasons I was asking. I tried downloading OR and for some reason I cannot get the thing to run on my computer.
Just my luck :-(

Click to expand...

You probably need to install the Java Runtine Environment dependency - https://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html

daveyfire said:

The Caliber ISP with a 29mm motor mount and no payload section is a Forte. It'll be a fine performer on F, G, H, and I motors.

But you could also build it without the payload section (for now) and leave the motor mount 54mm, flying 29s with an adapter. Then if you decide you ever want a Caliber ISP, plug one on and off you go 8)

Click to expand...

Very true. Might just do that.
Thanks